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Papers by Stephen Wraight

Research paper thumbnail of Molecular characterization and comparative virulence of Beauveria bassiana isolates (Ascomycota: Hypocreales) associated with the greenhouse shore fly, Scatella tenuicosta (Diptera: Ephydridae)

Research paper thumbnail of Application of modified atmosphere packaging (gas flushing and active packaging) for extending the shelf life of Beauveria bassiana conidia at high temperatures

Research paper thumbnail of Exotic Aphid Control with Pathogens

Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of ... more Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of these invasive pests are their small size, parthenogenetic reproduction, short generation time, ability for long distance dispersal by winged morphs, and their explosive population dynamics. Attention has mainly been focused on invasive aphid pests of economic importance to agriculture, horticulture, and forestry. More recently, however, concerns have also

Research paper thumbnail of Aphid hide-and-seek: why within-plant location of pests matters in a biological control program for multiple aphid species

During the application of biological control in any crop, a multi-species pest complex can compli... more During the application of biological control in any crop, a multi-species pest complex can complicate matters. Greenhouse floriculture growers in the Northeastern U.S., Canada, and the UK currently have to contend with both green peach aphid (Myzus persicae Sulzer) and foxglove aphid (Aulacorthum solani Kaltenbach). Previous short-term studies with the predator Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) indicate that this natural enemy prefers to oviposit in aphid patches on new plant growth, leading to differential attack rates for the two aphid species (A. solani preferring to feed on lower leaves). Here, we used longer-term trials to determine how these oviposition decisions affect control outcomes, and to see if crop growth stage had an effect. When both M. persicae and A. solani were present, control of M. persicae by A. aphidimyza was consistent at all plant stages, with 74 - 99% control achieved. In contrast, control of A. solani was inconsistent in the presence ...

Research paper thumbnail of Synergistic interaction between Beauveria bassiana- and Bacillus thuringiensis tenebrionis-based biopesticides applied against field populations of Colorado potato beetle larvae

Journal of Invertebrate Pathology, 2005

Commercial biopesticides based on the fungal pathogen Beauveria bassiana strain GHA and the bacte... more Commercial biopesticides based on the fungal pathogen Beauveria bassiana strain GHA and the bacterial pathogen Bacillus thuringiensis tenebrionis were applied alone and in combination (tank mixed) against larval populations of the Colorado potato beetle, Leptinotarsa decemlineata, in small plots of potatoes over three field seasons. Interactions between the two products were evaluated in terms of pest-control efficacy. B. bassiana (formulated

Research paper thumbnail of Application Parameters Affecting Field Efficacy of Beauveria bassiana Foliar Treatments against Colorado Potato Beetle Leptinotarsa decemlineata

Biological Control, 2002

The effects of various spray-application parameters on the efficacy of Beauveria bassiana foliar ... more The effects of various spray-application parameters on the efficacy of Beauveria bassiana foliar treatments against Leptinotarsa decemlineata larvae were evaluated during three field seasons. Treatments were applied to small plots (6 rows × 7–12 m) using a CO2-powered backpack hydraulic sprayer with nozzles affixed to lateral drop tubes and directed upward at a 45° angle to target ventral leaf surfaces.

Research paper thumbnail of Evaluation of the Entomopathogenic Fungi Beauveria bassiana and Paecilomyces fumosoroseus for Microbial Control of the Silverleaf Whitefly, Bemisia argentifolii

Biological Control, 2000

Collaborative research was conducted at the USDA-ARS Subtropical Agricultural Research Center in ... more Collaborative research was conducted at the USDA-ARS Subtropical Agricultural Research Center in southern Texas to assess the microbial control potential of Beauveria bassiana and Paecilomyces fumosoroseus against Bemisia whiteflies. Laboratory assays demonstrated the capacity of both pathogens to infect Bemisia argentifolii nymphs on excised hibiscus leaves incubated at relative humidities as low as 25% at 23 ± 2°C (ca. 35%

Research paper thumbnail of PROCESSOS DE GERMINAÇÃO DE ISOLADOS DO FUNGO Zoophthora radicans SOBRE Empoasca kraemeri

Scientia Agricola, 1996

... LG LEITE 1 ; SB ALVES 2 ; SP WRAIGHT 3 ; S. GALAINI-WRAIGHT 4 ; DW ROBERTS 4 1 ... The total ... more ... LG LEITE 1 ; SB ALVES 2 ; SP WRAIGHT 3 ; S. GALAINI-WRAIGHT 4 ; DW ROBERTS 4 1 ... The total production of germ tubes tended to be equal to that of capilliconidium on the host ... sphaerosperma) é bem conhecido no mundo por ser entomopatógeno polífago (Ben Ze'ev et ...

Research paper thumbnail of Liquid culture production of desiccation tolerant blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

Mycological Research, 1997

Liquid media with differing carbon concentrations and carbon-to-nitrogen ratios were tested for p... more Liquid media with differing carbon concentrations and carbon-to-nitrogen ratios were tested for production of desiccation tolerant blastospores of Paecilomyces fumosoroseus. While all media tested supported sporulation in submerged culture, high blastospore concentrations (5·8 × 108) spores ml−) were produced in media containing 80 g glucose l− and 13·2 g Casamino acids l− (MS medium) and a significantly higher percentage (79%) of these blastospores survived air drying. Media containing glucose concentrations greater than 20 g l − and Casamino acid concentrations between 13·2 and 40 g l− supported maximal production of desiccation tolerant blastospores. All 23 isolates of P. fumosoroseus grown in MS media produced high concentrations of desiccation tolerant blastospores. When stored at 4 °C, more than 60% of the lyophilized blastospores produced in MS medium were still viable after 7 months storage while less than 25% of the air-dried blastospores survived after 90 d storage. Standard whitefly bioassays were performed to compare air-dried blastospores of P. fumosoroseus ARSEF 4491 with solid substrate-produced conidia of Beauveria bassiana ARSEF 252. Air-dried blastospores of P. fumosoroseus gave LD50s of 60 and 113 blastospores mm− for the silverleaf whitefly (Bemisia argentifolii) in two separate bioassays with potency ratios (LD50B. bassiana/LD50P. fumosoroseus)of 3·9 and 3·8, respectively. These results have demonstrated that high concentrations of blastospores of P. fumosoroseus can be rapidly produced in liquid culture, remain viable following drying, and infect and kill silverleaf whitefly.

Research paper thumbnail of Transstadial Transmission of Pythium in Bradysia impatiens and Lack of Adult Vectoring Capacity

Phytopathology, 2010

Fungus gnats have been shown to transmit a variety of plant-pathogenic fungi that produce aerial ... more Fungus gnats have been shown to transmit a variety of plant-pathogenic fungi that produce aerial dispersal stages. However, few studies have examined potential interactions between fungus gnats and oomycetes, including Pythium spp. A series of laboratory experiments were conducted to determine whether fungus gnat adults are vectors of several common greenhouse Pythium spp., including Pythium aphanidermatum, P. irregulare, and P. ultimum. An additional objective was to determine whether P. aphanidermatum can be maintained transstadially in the gut of a fungus gnat larva through the pupal stadium to be transmitted by the subsequent adult. Adult fungus gnats did not pick up infectious Pythium propagules from diseased plants and transmit them to healthy plants in any experiment. Species-specific primers and a probe for real-time polymerase chain reaction were developed to detect the presence of P. aphanidermatum DNA in fungus gnat tissue samples. P. aphanidermatum DNA was detectable in the larval and pupal stages; however, none was detected in adult fungus gnats. These results are in agreement with previous studies that have suggested that adult fungus gnats are unlikely vectors of Pythium spp.

Research paper thumbnail of HABILIDADE DE INFECÇÃO DE ISOLADOS DE Zoophthora radicans SOBRE Empoasca kraemeri

Scientia Agricola, 1996

ABSTRACT Foram analisados e comparados os processos de germinação e habilidade de infecção dos is... more ABSTRACT Foram analisados e comparados os processos de germinação e habilidade de infecção dos isolados ARS-1590, ARS-1261 e ARS-1229 de Zoophthora radicans (Brefeld) Batko sobre ninfas do 5º ínstar de Empoasca kraemeri (Hoss & Moore) em ambiente de 20°C e 100% de umidade relativa. A formação de apressório e penetração dos isolados iniciaram-se dentro do período de seis horas após a inoculação. As penetrações dos isolados ocorreram em maior proporção no abdome, seguido do tórax e cabeça do inseto, tendo sido mais frequente nas membranas do corpo do que nos escleritos.

Research paper thumbnail of Strain-specific detection of introduced Beauveria bassiana in agricultural fields by use of sequence-characterized amplified region markers

Journal of Invertebrate Pathology, 2003

Research paper thumbnail of A tritrophic effect of host plant on susceptibility of western flower thrips to the entomopathogenic fungus Beauveria bassiana

Journal of Invertebrate Pathology, 2007

Research paper thumbnail of Acquisition of lethal doses of Beauveria bassiana conidia by western flower thrips, Frankliniella occidentalis, exposed to foliar spray residues of formulated and unformulated conidia

Journal of Invertebrate Pathology, 2005

Research paper thumbnail of Comparative virulence of Beauveria bassiana isolates against lepidopteran pests of vegetable crops

Journal of Invertebrate Pathology, 2010

Research paper thumbnail of Humoral encapsulation of the fungus Erynia radicans (Entomophthorales) by the potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae)

Journal of Invertebrate Pathology, 1988

Research paper thumbnail of Development of a novel bioassay for estimation of median lethal concentrations (LC50) and doses (LD50) of the entomopathogenic fungus Beauveria bassiana, against western flower thrips, Frankliniella occidentalis

Journal of Invertebrate Pathology, 2005

To conduct laboratory experiments aimed at quantifying secondary acquisition of fungal conidia by... more To conduct laboratory experiments aimed at quantifying secondary acquisition of fungal conidia by western flower thrips (Frankliniella occidentalis), an efficient assay technique using Beauveria bassiana as the model fungus was developed. Various application protocols were tested and it was determined that the percent mortality did not vary among protocols. Peak mortality of second-instar nymphs, under constant exposure to conidia, occurred 5 days post-inoculation. Second-instar thrips that were exposed to conidia within 24 h of the molt to second instar were more susceptible to Beauveria bassiana than thrips exposed after times greater than 24 h post-molt. Conidia efficacy, which was monitored at 24 h intervals, did not differ significantly within 72 h. A test of the final bioassay system was conducted in a series of assays aimed at determining the LD50 of B. bassiana technical powder against second-instar western flower thrips. It was determined that B. bassiana (strain GHA) is highly effective at very low doses (LD50 of 33-66 conidia/insect).

Research paper thumbnail of Description of a Zoophthora radicans (Zygomycetes: Entomophthoraceae) epizootic in a population of Empoasca kraemeri (Homoptera: Cicadellidae) on beans in central Brazil

Journal of Invertebrate Pathology, 1991

Research paper thumbnail of Debilitation in conidia of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and implication with respect to viability determinations and mycopesticide quality assessments

Journal of Invertebrate Pathology, 2010

Research paper thumbnail of Biology and Feeding Requirements of Larval Hunter Flies <I>Coenosia attenuata</I> (Diptera: Muscidae) Reared on Larvae of the Fungus Gnat <I>Bradysia impatiens</I> (Diptera: Sciaridae)

Journal of Economic Entomology, 2010

Research paper thumbnail of Molecular characterization and comparative virulence of Beauveria bassiana isolates (Ascomycota: Hypocreales) associated with the greenhouse shore fly, Scatella tenuicosta (Diptera: Ephydridae)

Research paper thumbnail of Application of modified atmosphere packaging (gas flushing and active packaging) for extending the shelf life of Beauveria bassiana conidia at high temperatures

Research paper thumbnail of Exotic Aphid Control with Pathogens

Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of ... more Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of these invasive pests are their small size, parthenogenetic reproduction, short generation time, ability for long distance dispersal by winged morphs, and their explosive population dynamics. Attention has mainly been focused on invasive aphid pests of economic importance to agriculture, horticulture, and forestry. More recently, however, concerns have also

Research paper thumbnail of Aphid hide-and-seek: why within-plant location of pests matters in a biological control program for multiple aphid species

During the application of biological control in any crop, a multi-species pest complex can compli... more During the application of biological control in any crop, a multi-species pest complex can complicate matters. Greenhouse floriculture growers in the Northeastern U.S., Canada, and the UK currently have to contend with both green peach aphid (Myzus persicae Sulzer) and foxglove aphid (Aulacorthum solani Kaltenbach). Previous short-term studies with the predator Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) indicate that this natural enemy prefers to oviposit in aphid patches on new plant growth, leading to differential attack rates for the two aphid species (A. solani preferring to feed on lower leaves). Here, we used longer-term trials to determine how these oviposition decisions affect control outcomes, and to see if crop growth stage had an effect. When both M. persicae and A. solani were present, control of M. persicae by A. aphidimyza was consistent at all plant stages, with 74 - 99% control achieved. In contrast, control of A. solani was inconsistent in the presence ...

Research paper thumbnail of Synergistic interaction between Beauveria bassiana- and Bacillus thuringiensis tenebrionis-based biopesticides applied against field populations of Colorado potato beetle larvae

Journal of Invertebrate Pathology, 2005

Commercial biopesticides based on the fungal pathogen Beauveria bassiana strain GHA and the bacte... more Commercial biopesticides based on the fungal pathogen Beauveria bassiana strain GHA and the bacterial pathogen Bacillus thuringiensis tenebrionis were applied alone and in combination (tank mixed) against larval populations of the Colorado potato beetle, Leptinotarsa decemlineata, in small plots of potatoes over three field seasons. Interactions between the two products were evaluated in terms of pest-control efficacy. B. bassiana (formulated

Research paper thumbnail of Application Parameters Affecting Field Efficacy of Beauveria bassiana Foliar Treatments against Colorado Potato Beetle Leptinotarsa decemlineata

Biological Control, 2002

The effects of various spray-application parameters on the efficacy of Beauveria bassiana foliar ... more The effects of various spray-application parameters on the efficacy of Beauveria bassiana foliar treatments against Leptinotarsa decemlineata larvae were evaluated during three field seasons. Treatments were applied to small plots (6 rows × 7–12 m) using a CO2-powered backpack hydraulic sprayer with nozzles affixed to lateral drop tubes and directed upward at a 45° angle to target ventral leaf surfaces.

Research paper thumbnail of Evaluation of the Entomopathogenic Fungi Beauveria bassiana and Paecilomyces fumosoroseus for Microbial Control of the Silverleaf Whitefly, Bemisia argentifolii

Biological Control, 2000

Collaborative research was conducted at the USDA-ARS Subtropical Agricultural Research Center in ... more Collaborative research was conducted at the USDA-ARS Subtropical Agricultural Research Center in southern Texas to assess the microbial control potential of Beauveria bassiana and Paecilomyces fumosoroseus against Bemisia whiteflies. Laboratory assays demonstrated the capacity of both pathogens to infect Bemisia argentifolii nymphs on excised hibiscus leaves incubated at relative humidities as low as 25% at 23 ± 2°C (ca. 35%

Research paper thumbnail of PROCESSOS DE GERMINAÇÃO DE ISOLADOS DO FUNGO Zoophthora radicans SOBRE Empoasca kraemeri

Scientia Agricola, 1996

... LG LEITE 1 ; SB ALVES 2 ; SP WRAIGHT 3 ; S. GALAINI-WRAIGHT 4 ; DW ROBERTS 4 1 ... The total ... more ... LG LEITE 1 ; SB ALVES 2 ; SP WRAIGHT 3 ; S. GALAINI-WRAIGHT 4 ; DW ROBERTS 4 1 ... The total production of germ tubes tended to be equal to that of capilliconidium on the host ... sphaerosperma) é bem conhecido no mundo por ser entomopatógeno polífago (Ben Ze'ev et ...

Research paper thumbnail of Liquid culture production of desiccation tolerant blastospores of the bioinsecticidal fungus Paecilomyces fumosoroseus

Mycological Research, 1997

Liquid media with differing carbon concentrations and carbon-to-nitrogen ratios were tested for p... more Liquid media with differing carbon concentrations and carbon-to-nitrogen ratios were tested for production of desiccation tolerant blastospores of Paecilomyces fumosoroseus. While all media tested supported sporulation in submerged culture, high blastospore concentrations (5·8 × 108) spores ml−) were produced in media containing 80 g glucose l− and 13·2 g Casamino acids l− (MS medium) and a significantly higher percentage (79%) of these blastospores survived air drying. Media containing glucose concentrations greater than 20 g l − and Casamino acid concentrations between 13·2 and 40 g l− supported maximal production of desiccation tolerant blastospores. All 23 isolates of P. fumosoroseus grown in MS media produced high concentrations of desiccation tolerant blastospores. When stored at 4 °C, more than 60% of the lyophilized blastospores produced in MS medium were still viable after 7 months storage while less than 25% of the air-dried blastospores survived after 90 d storage. Standard whitefly bioassays were performed to compare air-dried blastospores of P. fumosoroseus ARSEF 4491 with solid substrate-produced conidia of Beauveria bassiana ARSEF 252. Air-dried blastospores of P. fumosoroseus gave LD50s of 60 and 113 blastospores mm− for the silverleaf whitefly (Bemisia argentifolii) in two separate bioassays with potency ratios (LD50B. bassiana/LD50P. fumosoroseus)of 3·9 and 3·8, respectively. These results have demonstrated that high concentrations of blastospores of P. fumosoroseus can be rapidly produced in liquid culture, remain viable following drying, and infect and kill silverleaf whitefly.

Research paper thumbnail of Transstadial Transmission of Pythium in Bradysia impatiens and Lack of Adult Vectoring Capacity

Phytopathology, 2010

Fungus gnats have been shown to transmit a variety of plant-pathogenic fungi that produce aerial ... more Fungus gnats have been shown to transmit a variety of plant-pathogenic fungi that produce aerial dispersal stages. However, few studies have examined potential interactions between fungus gnats and oomycetes, including Pythium spp. A series of laboratory experiments were conducted to determine whether fungus gnat adults are vectors of several common greenhouse Pythium spp., including Pythium aphanidermatum, P. irregulare, and P. ultimum. An additional objective was to determine whether P. aphanidermatum can be maintained transstadially in the gut of a fungus gnat larva through the pupal stadium to be transmitted by the subsequent adult. Adult fungus gnats did not pick up infectious Pythium propagules from diseased plants and transmit them to healthy plants in any experiment. Species-specific primers and a probe for real-time polymerase chain reaction were developed to detect the presence of P. aphanidermatum DNA in fungus gnat tissue samples. P. aphanidermatum DNA was detectable in the larval and pupal stages; however, none was detected in adult fungus gnats. These results are in agreement with previous studies that have suggested that adult fungus gnats are unlikely vectors of Pythium spp.

Research paper thumbnail of HABILIDADE DE INFECÇÃO DE ISOLADOS DE Zoophthora radicans SOBRE Empoasca kraemeri

Scientia Agricola, 1996

ABSTRACT Foram analisados e comparados os processos de germinação e habilidade de infecção dos is... more ABSTRACT Foram analisados e comparados os processos de germinação e habilidade de infecção dos isolados ARS-1590, ARS-1261 e ARS-1229 de Zoophthora radicans (Brefeld) Batko sobre ninfas do 5º ínstar de Empoasca kraemeri (Hoss &amp; Moore) em ambiente de 20°C e 100% de umidade relativa. A formação de apressório e penetração dos isolados iniciaram-se dentro do período de seis horas após a inoculação. As penetrações dos isolados ocorreram em maior proporção no abdome, seguido do tórax e cabeça do inseto, tendo sido mais frequente nas membranas do corpo do que nos escleritos.

Research paper thumbnail of Strain-specific detection of introduced Beauveria bassiana in agricultural fields by use of sequence-characterized amplified region markers

Journal of Invertebrate Pathology, 2003

Research paper thumbnail of A tritrophic effect of host plant on susceptibility of western flower thrips to the entomopathogenic fungus Beauveria bassiana

Journal of Invertebrate Pathology, 2007

Research paper thumbnail of Acquisition of lethal doses of Beauveria bassiana conidia by western flower thrips, Frankliniella occidentalis, exposed to foliar spray residues of formulated and unformulated conidia

Journal of Invertebrate Pathology, 2005

Research paper thumbnail of Comparative virulence of Beauveria bassiana isolates against lepidopteran pests of vegetable crops

Journal of Invertebrate Pathology, 2010

Research paper thumbnail of Humoral encapsulation of the fungus Erynia radicans (Entomophthorales) by the potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae)

Journal of Invertebrate Pathology, 1988

Research paper thumbnail of Development of a novel bioassay for estimation of median lethal concentrations (LC50) and doses (LD50) of the entomopathogenic fungus Beauveria bassiana, against western flower thrips, Frankliniella occidentalis

Journal of Invertebrate Pathology, 2005

To conduct laboratory experiments aimed at quantifying secondary acquisition of fungal conidia by... more To conduct laboratory experiments aimed at quantifying secondary acquisition of fungal conidia by western flower thrips (Frankliniella occidentalis), an efficient assay technique using Beauveria bassiana as the model fungus was developed. Various application protocols were tested and it was determined that the percent mortality did not vary among protocols. Peak mortality of second-instar nymphs, under constant exposure to conidia, occurred 5 days post-inoculation. Second-instar thrips that were exposed to conidia within 24 h of the molt to second instar were more susceptible to Beauveria bassiana than thrips exposed after times greater than 24 h post-molt. Conidia efficacy, which was monitored at 24 h intervals, did not differ significantly within 72 h. A test of the final bioassay system was conducted in a series of assays aimed at determining the LD50 of B. bassiana technical powder against second-instar western flower thrips. It was determined that B. bassiana (strain GHA) is highly effective at very low doses (LD50 of 33-66 conidia/insect).

Research paper thumbnail of Description of a Zoophthora radicans (Zygomycetes: Entomophthoraceae) epizootic in a population of Empoasca kraemeri (Homoptera: Cicadellidae) on beans in central Brazil

Journal of Invertebrate Pathology, 1991

Research paper thumbnail of Debilitation in conidia of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and implication with respect to viability determinations and mycopesticide quality assessments

Journal of Invertebrate Pathology, 2010

Research paper thumbnail of Biology and Feeding Requirements of Larval Hunter Flies <I>Coenosia attenuata</I> (Diptera: Muscidae) Reared on Larvae of the Fungus Gnat <I>Bradysia impatiens</I> (Diptera: Sciaridae)

Journal of Economic Entomology, 2010